<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
       .bw1{
           /* float: left; */
           width: 400px;
           height: 400px;
           background-color: red;
       }
       .bw2{
           width: 350px;
           height: 350px;
           float: left;
           background-color: green;
       }
       .bw3{
           width: 350px;
           height: 350px;
           float: left;
           background-color: green;
       }
    </style>
</head>
<body>
        <div class="bw3">333</div>
    <div class="bw1">1</div>
    <div class="bw2">22</div>
   
</body>
</html>